Large audience 3D display system without glasses

ABSTRACT

A three dimensional (3D) display apparatus for without 3D glasses. The display apparatus includes a display element operated to display left and right eye images. A back light assembly back lights the display element and includes light bars with a row of infrared (IR) light receivers that are each paired to a white light emitting diode (LED). Viewers in seats in tiered rows such that their heads are in known viewing locations. Left and right side illuminators illuminate the left and right sides of the faces of the viewers with IR light. The IR light is synchronized with display of the left and right eye images. IR reflected from viewers&#39; faces pass through the display element and is focused onto IR light receivers, which causes LEDs to emit light onto the display element and provide left or right eye images to the viewers at their left or right eyes.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/717,214, which was filed on Dec. 17, 2012, which is herebyincorporated by reference in its entirety.

BACKGROUND

1. Field of the Description

The present invention relates, in general, to devices and methods forproviding a three-dimensional (3D) display in a glasses-free manner,and, more particularly, to a 3D display device providing back lightingand optics to present left and right eye images to each viewer's leftand right eye, respectively, regardless of the position of the viewerwithin a viewer space (e.g., regardless of whether the viewer is in thefront row or back row of a theater or ride vehicle with tiered seatingand whether the viewer moves their head from side-to-side while viewingthe 3D movie or display).

2. Relevant Background

Displays that provide the illusion of three dimensions have experienceda rebirth in the past few years. For example, a number of 3D televisionsare now available for use in homes and home theaters. These 3Dtelevisions generally operate by displaying a stream of left and righteye images in an alternating or time-multiplexed manner (e.g.,left-right-left-right). Switching occurs so quickly that the viewer doesnot sense a flicker or change in the display. The viewer wears specialheadgear or glasses that operate in a synchronized manner with thedisplay to only allow the light associated with the left eye image toreach the viewer's left eye and with the right eye image to reach theviewer's right eye.

For example, the 3D glasses may be shutter glasses that rapidly switchbetween allowing light to reach the left or the right eye, with theshuttering operation controlled to be time-synchronized with the display(e.g., a liquid crystal display (LCD) television monitor or the like).In other cases, the television monitor or display is configured tooutput two different types of polarized light to present the left andright eye images. In this case, the viewer typically wears glasses withtwo different lenses that are polarized in a manner to allow the lefteye to view light from the display polarized in one manner and the righteye to view light from the display polarized in a second manner. Suchpolarized 3D glasses have been in use in theaters for many years.

While most commercial displays rely on the use of special glasses, it isgenerally agreed by those in the 3D entertainment industry that displaysable to provide a 3D viewing experience without glasses or headgearoffer significant advantages. Presently, there are 3D display systemsthat can deliver left eye images to a viewer's left eye and right eyeimages to a viewer's right eye. However, these 3D display systems eachhave significant limitations. Some 3D display systems require the viewerto have their head in a specific position and to not move at all duringthe viewing experience as this may cause the wrong image to be viewed(e.g., the right eye to see the left eye image stream or vice versa) orto lose the image altogether. In other implementations, the viewer canmove but complex tracking equipment is used to identify an approximatelocation of the viewer's eyes. The 3D display system then reacts to thenew position by changing the output of the display to deliver the leftand right eye images to the viewer. Both of these systems are generallylimited to use with a relatively small audience, such as 1 to 4 viewersor the like, and these systems may be expensive to design andmanufacture, which has resulted in only very limited adoption of such 3Ddisplay systems nationwide.

Hence, there remains a need for display technology that can provide 3Dstereo images to audiences without the need for the audience members orviewers to wear glasses or special headgear. Preferably, such displaytechnology would be suited for larger audiences of up to 20 to 40 ormore members/viewers. Further, it is desirable that the technology berelatively inexpensive to implement (although this may not be alimitation in some settings) so as to allow more widespread useincluding home theater settings. Additionally, the 3D display technologyshould be adapted such that the viewers do not have to remain in oneposition throughout the experience (e.g., can move their head) and canbe at various heights and viewing distances (e.g., seated in a theateror ride vehicle with rows of seats that are tiered with each row beingfurther from the screen and higher from a reference plane to allowviewing that is unobstructed by viewers in lower rows).

SUMMARY

A 3D display system is described that addresses many of the problemsassociated with prior 3D displays in that the viewers do not have towear glasses or headgear, can move during the viewing within a viewingspace (at least within a predefined range of movements), and can be atdiffering viewing distances and heights. The 3D display system providesthe capability of 3D viewing without glasses where it is knownbeforehand a general space or volume where each viewer's head will bepositioned as is the case for a theater with seating and a vehicle ride.For example, a ride system may be adapted for providing 3D viewing, andpassengers/viewers are strapped into seats while they are watching a 3Dimage. Similarly, a theater with individual seats (and, in some cases,bench seats) can be used as part of the viewing space of the 3D displaysystem. In both of these examples, each of the viewers' heads is in aknown position such as within a box that accounts for varying viewerheights. Further, the 3D display system is designed to provide stereofor each viewer or audience member even over a relatively large range ofleft, right, up, and down head movements (e.g., if the viewer remainsseated or in a first anticipated position, they can move their head andstill experience 3D images).

In one embodiment or implementation of a 3D display system, viewers viewthe 3D image on a large, but otherwise ordinary LCD monitor with thebacklight removed (sometimes called a transparent LCD or LC display,herein). A similarly sized Fresnel lens (or other lens or lens system)is positioned behind (opposite the viewer side or display surface of theLC display) the LC display. The 3D display system includes two infrared(IR) light sources (e.g., invisible light sources such as IR LED lights)that are placed on the right and left side of each viewer and arrangedto provide their light onto the viewer's face on the right and leftside. These two lights are synchronized with the displaying of the leftand right eye images on the LC display (e.g., left side of the face orarea near their left eye is illuminated with IR light concurrently withdisplay of the left eye image).

IR light reflected from the viewer's face (location of their eyes at thepresent time) passes through the LC display (i.e., LCD materials aretypically transparent to IR light). This IR light is then focused by theFresnel or other lens onto a thin horizontal strip of IR light detectorsor sensors. Each of these sensors/detectors is matched or paired with abright white LED emitter. In this manner, the image of a left or rightside of the viewer's face is focused onto the strip of IR sensors, whichresults in one or more of the LED emitters being turned on so as tolight up in bright white light at a location that matches or isproximate to (within 1 to 2 inches) the position of the IR sensor, whichwas hit by the IR light from the viewer's face (or approximate eyelocation).

This bright white light passes back along the same (or nearly the same)optical path as the IR light to pass through the lens and light up(provide back lighting of) the LCD so as to light up the appropriateside of the viewer's face (e.g., deliver the left or right eye image tothe left or right eye of the viewer). In other words, the returninglight from the LED emitter is “carrying” the image of the entire LCDappropriate to the particular viewer's eye. No one else in the viewingspace (e.g., a theater) can see this light since it is exactly (ornearly so) and reciprocally being delivered to the specificviewer/audience member. The 3D display system is configured to providethis same action to every viewer or member in the audience as eachviewer is receiving their eye-specific image from the LCD at theirspecific eye location in the viewing space. Because substantially all ofthe light from a lit visible light emitter is directed towards viewers'faces and eyes, the system can operate at a very high optical efficiencyand can provide high brightness images for the audience using relativelylittle power.

In another embodiment or implementation of a 3D display system, the leftand right sides of a viewer's face are continuously lit by two differentwavelengths of infrared light (e.g., IR LED1 and IR LED2 providingwavelengths 1 and 2). Again, both wavelengths pass through the LCD andlens system to now focus on two light bars behind the LCD per seat (orviewer position). One light bar accepts wavelength 1 and the otherwavelength 2. The white light emitters (white LEDs) for the two lightbars have polarizers so that, for instance, IR light from the left sideof the viewer's face is emitted back towards the viewer as verticallypolarized white light and the other side as horizontally polarized whitelight. The LC display may be configured to show different images on thesame screen based on the polarization of the light that is separatelyand directionally used to back light the LC display. The viewer onlyperceives left eye-destined light in their left eye and righteye-destined light in their right eye, which creates a smooth stereoviewing experience.

Interestingly, the IR-to-visible light bars are set up or positionedbehind the LC display (or viewing screen) in places that are optically“conjugate” with the theater/vehicle seating (e.g., the expectedpositions of the viewer's eyes). In other words, the light bars areprovided as tiered rows to match the tiered rows of the viewers' seats.This innovative technique allows the viewers to be served (with perfectfidelity) the stereo images (or 3D images) even though they are atvarying distances from the screen and heights relative to a lowerreference plane (e.g., a theater floor supporting the first or lowestrow). In addition, the light bars may be curved to match the Petzvalfocusing surface of the optical focusing element.

In the above-discussed embodiments, vertical scattering is typicallyprovided between the output of the light bars and the back side/surfaceof the LC display to provide a vertical strip of light to be deliveredto the viewer's face. This accounts for viewer's moving their heads upand down and also provides a larger vertical payload of light to theviewer's face to increase the likelihood that the light will bedelivered to their eye. Vertical scattering may be provided with anoptical layer that is vertically scattering but horizontallytransparent, and this may be provided with a sheet of horizontallenticular array material, a vertically diffusing holographic film, orthe like. The vertical diffuser (or vertical scattering film/layer) ispositioned adjacent to the light bar or to the Fresnel lens and LCD(e.g., between the LC display and the light bar). This material makesthe bundled light rays in the system more cylindrical (e.g., notdependent on the vertical position of the viewer or of the horizontallight strips). This means that viewers sitting in tiered rows are easilyserved and also that the placement of the horizontal light bars(horizontal rows of IR detectors and white LEDs) only has to be at thecorrect distance and angle to the screen (LC display) but can be mountedwith relaxed height tolerances (as the vertical diffuser provides sometolerances/play).

More particularly, a display apparatus is provided that includes adisplay element and a display controller that first displays a left eyeimage and second displays a right eye image on or with the displayelement. The display apparatus also includes, within a viewing spaceadjacent a display surface of the display element, an illuminatorassembly operable to provide infrared (IR) light in the viewing space.Further, the display apparatus includes a back light assembly thatfunctions to generate visible light to back light the display element.The visible light is emitted in response to reflection of portions ofthe IR light from one or more viewers positioned at viewing locations inthe viewing space.

In some embodiments, the display element includes a liquid crystal (LC)display that is transparent to the reflected portions of the IR light,whereby the reflected portions of the IR light passes through thedisplay element. In such embodiments, the back light assembly mayinclude a light bar made up of a row of IR receivers detecting thereflected portions of the IR light and a row of visible light sourceseach operating in response to one of the IR receivers detecting thereflected portions of the IR light. The display apparatus may include afocusing element positioned between the LC display and the light bar tofirst focus the reflected portions of the IR light onto the row of theIR receivers and to second focus light from the visible light sourcesinto the viewing space through the LC display, whereby the LC display isback lighted.

In some cases, each of the IR receivers is paired with one of thevisible light sources and each of the visible light sources comprises awhite light emitting diode (LED). In some particular implementations,the paired ones of the LEDs and the IR receivers are spaced apart lessthan 1 inch horizontally so as to provide adequate horizontaleye-position density in the conjugate viewing positions in front of thedisplay, and a receiving surface of the IR receiver and a light emittingsurface of the LED are spaced apart an offset distance with thereceiving surface more distal to the LC display. Further, the IR lightmay be IR modulated at 38 kHz and the IR receivers may be configured fordetecting IR modulated at 38 kHz.

According to another aspect of the display apparatus, the illuminatorassembly includes a number of left side IR illuminators and a number ofright side IR illuminators. Each of the left and ride side IRilluminators may include an IR source and a collimator for generatingthe IR light to the viewing space. Each of the left side IR illuminatorsmay be directed towards a left side of one or more of the viewerlocations, and each of the right side IR illuminators may be focusedonto a right side of one or more of the viewer locations. In such cases,the illuminator assembly may be operated in a time synchronized mannerwith the display element, whereby the left side IR illuminators operateconcurrently with the first displaying and the right side IRilluminators operate concurrently with the second displaying. Further,the viewing space may include a number of tiered rows of individualseats for defining the viewing locations for the viewers and wherein theback light assembly comprises the number of the rows of the IR receiversand the visible light emitters arranged in tiers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic and/or functional block diagram of a 3Ddisplay system that is particularly useful in providing an audience ofviewers a 3D viewing experience without requiring special headgear suchas 3D glasses and while allowing the viewers to sit (or be positioned)at numerous viewing positioned (e.g., in any seat in any of a number oftiered rows as is common in a theater or in a vehicle of an amusementpark);

FIG. 2 illustrates a diagram of one exemplary implementation of a 3Ddisplay system that may be used to provide the components and/orfunctionality of the system of FIG. 1;

FIG. 3 illustrates a diagram of a 3D display system similar to that ofFIG. 2 with modifications to show use of multiple, tiered rows of lightbars (row of IR detector and white LED pairs) to serve stereo images toa viewing space associated with a seat (or other viewer positioningdevice) in one of multiple, tiered rows of such individual seats (orviewer positioning devices);

FIG. 4 illustrates the 3D display system of FIG. 3 operating to providea left eye image to a viewer in back or third row of the viewing space;

FIG. 5 illustrates the 3D display system of FIGS. 3 and 4 operating toconcurrently provide left eye images to each viewer in the three rows ofthe viewing space (e.g., in individual seats of tiered rows of a theateror ride vehicle);

FIG. 6 is a perspective view of an exemplary light bar that may be usedin a 3D display system such as the system of FIG. 3;

FIG. 7 is a view of a light bar similar to that of FIG. 6 that ismodified to place the IR detectors further away from a focusing elementsuch as a Fresnel lens to account for the differing (greater) focaldistance of IR relative to visible light used to back light the LCdisplay;

FIG. 8 illustrates a portion of a back light assembly that utilizesoffset IR receivers and visible light emitters as well as horizontal andvertical diffusers to condition light used to back light an LC display(or other display element);

FIG. 9 illustrates a perspective view of a back light assembly usingthree light bars to serve left and right eye images (stereo images) toviewers/audience members placed in three, tiered rows in a viewing space(e.g., theater, 3D ride vehicle, or the like);

FIGS. 10A-10C illustrate three embodiments back light assemblies showinga schematic of one IR receiver/detector and visible light emitter pair;

FIG. 11 is a schematic or functional block drawing of a portion of a 3Ddisplay system showing a sync signal generator for use in controllingoperation of left and right collimated illuminators in a manner that istime synchronized with an LC display to display left and right eyeimages;

FIG. 12 is a functional diagram of another implementation of a 3Ddisplay system making use of a video light bar to serve as a back light;

FIG. 13 is a diagram of an implementation of a 3D display system usingan out-front camera to provide IR tracking that can be used toselectively drive operation of visible light sources arranged in anarray (horizontal rows of white LEDs or the like stacked and/or tiered);

FIGS. 14 and 14A are diagrams of a 3D display system making use of acurved or cylindrical reflector in a back light assembly to provideoptical paths for focused IR light and emitted visible light to backlight a display element;

FIG. 15 shows another 3D display system using a spherical reflector aspart of the back light assembly;

FIG. 16 provides a diagram of yet another 3D display system usingpolarizers to display left and right eye images to a viewer;

FIG. 17 illustrates a 3D display system similar to that of FIG. 16 butwith a differing location of the polarization rotator;

FIG. 18 illustrates a 3D display system similar to the systems of FIGS.16 and 17 but using a switch polarizer with code;

FIG. 19 shows a 3D display system using a pair of light bars per row ofviewers that are used in a switched manner to show left and right framesof a 3D video stream;

FIG. 20 illustrates another 3D display system similar to the system ofFIG. 19 that further makes use of a head tracking camera;

FIG. 21 shows a 3D display system making use of a beam splitter combinedwith a pair of focusing elements to provide a 3D experience to viewerswithout the need for shuttered or other 3D glasses or headgear; and

FIG. 22 illustrates a system using a turning film mounted in front of anLC display to provide 3D images without glasses to a wider swath ofviewers.

DETAILED DESCRIPTION

Briefly, the present description is directed toward a 3D display systemthat uses invisible infrared (IR) light to determine the presentlocation of each viewer's left and right eyes in an audience that mayinclude 1 to many members. The viewers may be, for example, seated inindividual seats in theater or vehicle ride so that their heads are inknown positions (e.g., accounting for height ranges and some range ofside-to-side head movement such as in a known 3D space, volume, or “headbox” that should contain each viewer's head). An IR light source isprovided for the left and right side of each viewer's face and directsits light into the head box or viewer's eye-location space.

When a viewer is present in a seat/position, the IR light is reflectedfrom their right or left side of their face (e.g., their left or righteye location). A 3D display device such as an LC display is used toalternate or switch between displaying a right and a left eye image (3Dmedia stream made of right and left eye images), and the IR sources aretime synchronized to operate with the 3D display device to illuminatethe left side of each viewer's face when the left image is displayed andthe right side when the right image is displayed. The 3D display deviceis transparent to IR such that a portion of the face-reflected IR lightpasses through the 3D display device (e.g., LCD with its back lightremoved).

A lens such as a large, planar Fresnel lens is positioned behind the 3Ddisplay device and acts to focus the IR light onto a light bar with arow of IR detectors each paired with a white light source (e.g., abright, white light emitter such as an LED). When reflected IR light isdetected by an IR detector, the light source paired with or associatedwith that detector is operated to emit white light (from nearly the samelocation as the IR detector) back towards the lens along the same ornearly the same optical path. The lens focuses the white light throughthe 3D display device (e.g., LC display) so as to provide a backlighting of the left or right image being displayed by the 3D displaydevice. As a result, the light from the 3D display is emitted from thefront surface of the 3D display so as to illuminate or strike the leftor right side of the viewer's face (depending on whether the IR lightthat initiated this back lighting operation originated from the viewer'sleft or right side). In this way, each viewer in an audience receivesleft eye images with their left eye and right eye images with theirright eye, and there is no need for 3D glasses or any special headgear.

Prior to describing several particular implementations of systemcomponents, it may be useful to first provide a discussion of an overall3D display system and operation of its various components to eliminatethe need for viewers to wear 3D glasses to view a 3D movie or other 3Dmedia.

FIG. 1 illustrates a 3D display system 100 for use in providing a viewer105 a 3D experience without the need for special glasses. The viewer 105is shown to be positioned in a viewing space or volume 102 such as theinterior of a movie theater, a home theater or a room in a house, avehicle of an amusement park ride, and so on. The viewer 105 is in aseat 108 such as within any of a number of seats in any of a number oftiered rows of such seats 108. In other words, 3D display system 100 isshown in simplified form with only one viewer 105 and seat 108, but atypical 3D display system 100 would include 2 to 20 or more seatsarranged in rows that are each at differing heights.

In this manner, each seat 108 places the viewer 105 at a differentviewing distance from a front of display surface 112 of a displayelement 110 and also at a different viewing height as shown in FIG. 1 asbeing measured generally as the distance from the viewer's eyes 106, 107and the surface 112 and the height of the eyes 106, 107 relative tofloor or lower portions of the viewing space 102 (e.g., each successiverow of seats 108 is some amount higher than the prior row (as is commonin movie theaters and vehicles for 3D rides to provide each viewer 105with a clearer view of the surface 112)).

The 3D display system 100 includes a display element 110 that, duringoperations of the system 100, functions to switch between or alternateback and forth between display of a left eye image 114 and a right eyeimage 116. This occurs synchronously with back lighting from a backlight assembly 170, and the light associated with the left eye (L.E. inthe figure) image 115 and the light associated with the right eye (R.E.in the figure) image 117 are directed outward into the viewing space 102to the left and right eyes 106, 107, respectively (as discussed furtherbelow) of the viewer 105. More specifically, switching between eachimage 114, 116 may occur so rapidly that the viewer 105 cannot perceiveany flicker with each image 114, 116 only displayed for a small fractionof a second (e.g., the left eye image 114 is displayed 60 times persecond alternately with the 60 times per second display of the right eyeimage 116 or some other useful switching time for the images on surface112).

The 3D display system 100 also includes a display controller or mediasource 120 that functions to selectively retrieve from memory or adigital image buffer 122 the digital right and left eye images 124, 126(e.g., right and left eye images or frames of a 3D movie or the like).The controller 120 alternatively (time multiplexed) provides the imagesignals 125, 127 to the display element 110 for display via 112 as shownat 114 and 116. Operation of the media source/controller 120 and displayelement 110 may be similar to that of a conventional 3D television ordisplay device that prior to the present invention had to be viewedusing shuttered or polarized 3D glasses or other special headgear. Forexample, a conventional 3D television may be modified to implement the3D display system 100 by replacing the back light components of a liquidcrystal display (LCD) monitor with the focusing element 160 and the backlight assembly 170 and by outputting left/right eye timing data/signals134 to a system controller 130. In some systems 100, the display element110 takes the form of a selectively transparent emissive display such asa transparent LCD panel or screen (or “transparent LC display”). Themedia source 120 may take the form of the 3D television control softwareand hardware.

To achieve a 3D experience without the need for glasses/headgear, the 3Ddisplay system 100 includes left and right eye infrared (IR) lightsources 140, 141. The left eye IR light source 140 includes an IRbulb/light source 142 and its output is modified by a collimator orsimilar device 144 to provide left eye IR light 146 that is directedonto the left eye 106 of the viewer 105. The collimator 144 is providedsuch that the IR light 146 is generally rectangular in cross sectionalshape in the area where the face of the viewer 105 is positioned. Thisis shown with the dashed box 148 that has a width, w, and a height, h(but, in practice the “box” 148 may be more irregular in shape). Thesize and shape of this IR light box (or head box) 148 is chosen, via thepositioning of the IR light source 140 and configuration of thecollimator 144, based on the position of the seat 108 in the viewingspace so as to direct the IR light 146 onto a viewer 105 in the seat 108and further to try to account for an expected eye location verticalrange (shown in FIG. 1). This range is used to account for the differingheight of viewers 105 that may use the seat 108 (e.g., small children upto taller adults). In one embodiment, the width, w, is in the range of 6to 20 inches and the height, h, is in the range of 12 to 36 inches (ormore), with the center of the box 148 generally being positioned atabout the center of the expected vertical range of eye locations.

In this manner, the left eye IR light source 140 can be operated to“light up” the left side of the face of the viewer 105 including thearea near the left eye 106. In a similar manner, the right eye IR lightsource 141 may be operated to provide right eye IR light 147 that has abox or other cross sectional shape as shown at 149. The IR light 147strikes the right side of the face of the viewer 105 including in areasnear the right eye 107.

The operation of the left and right eye IR light sources 140, 141 iscontrolled by sync/control signals 136, 138 provided in a switching ortime multiplexed manner by a system controller 130. Hence, the left eyeIR light 146 is provided during a first time period, the right eye IRlight 147 is then provided in a second time period (with the left eye IRlight source 140 being off or not providing light 146), and this isrepeated during operation of the system 100. The duration of these timeperiods is matched to the time periods of the display of left and righteye images 114, 116 on the display element 110 by the controller 120.Similarly, the initiation of each IR pulse 146, 147 is synchronized withthe signals 125, 127.

To this end, the system controller 130 includes a synchronizationelement or device 132 that operates to provide the control signals 136,138 in a time synchronized manner relative to signals 125, 127. In otherwords, the 3D display system 100 operates to provide the left eye IRlight 146 when the left eye images 127 are being used to operate thedisplay element 110 and to provide the right eye IR light 147 when theright eye images 125 are being used to operate the display element 110.In one example, the timing data/signals 134 provided by the displaycontroller 120 are the control signals intended for use in operating theleft and right shutters of 3D shutter glasses intended for use withdisplay element 110. In this way, when a left eye shutter would open,the left eye IR light 146 is provided by source 140 and when a right eyeshutter would open the right eight IR light 147 is provided by source141 (or light 146, 147 is not provided when a corresponding glassshutter is signaled to be closed by controller 120).

When “illuminated,” the face of the viewer 105 alternately reflects theleft and right eye IR light 146, 147. A portion of this light isreflected toward the front/display surface 112 of the display element110 as is shown with arrows 150, 151, respectively. Significantly, thereflected L.E. IR 150 and reflected R.E. IR 151 originates from an areamatching or at least generally corresponding with the present positionof the left eye 106 and the right eye 107, respectively, of the viewer105. The viewer 105 may move their head, and this would change thelocation of the eyes 106, 107. The 3D display system 100 is adapted toallow or compensate for such movement of the eyes 106, 107 whilecontinuing to provide left and right eye images 115, 117 to the samearea corresponding to the left and right eyes 106, 107 as was used foror involved in providing the reflected IR 150, 151. In other words, theleft and right eye images 115, 117 substantially follow the same opticalpath as the reflected IR 150, 151, respectively, to ensure that the leftand right images 114, 116 are viewed by the left and right eyes 106,107.

To provide the left and right eye images 115, 117 on the same (or nearlyso) optical path as reflected IR light 150, 151, the 3D display system100 includes a focusing element 160 and a back light assembly 170 thatare both positioned on a back side of the display element 110 (e.g., ina space opposite the viewing space 102). The display element 110 ischosen to be transparent to IR light including light 150, 151, and thismay be achieved with a transparent LC display or similar display screen.As a result, the reflected IR light 150, 151 passes through the displayelement 110, and, when it strikes the focusing element 160, it isfocused onto one of a plurality of IR sensors 172 provided in the backlight assembly 170 as is shown with arrows 162, 163. The focusingelement 160 may take a number of forms such as a planar, Fresnel lens,which may be sized and shaped to match the shape and size of the displayelement 110 (or be somewhat larger or smaller than the display element110 in some cases).

For example, the IR sensors 172 may be arranged in tiered rows such aswith a first row having a plurality of sensors 172, a second row havinga plurality of sensors 172 that is further away from the display element110 and at a second height that is greater than the height of the firstrow, and so on. The number of rows of sensors 172 may be chosen to matchthe number of rows of seats 108 in the viewing space. Similarly, thewidth of the rows, number of sensors 172, and spacing between adjacentpairs of sensors 172 may be varied to practice the 3D display system 100and will typically be selected so that at least a portion of the focusedIR light 162, 163 strikes one or more IR sensor 172. The sensitivity ofthe IR sensors 172 is also chosen to match the intensity of the IR light162, 163 (e.g., the IR sources 142, 143 along with the fractionreflected 150, 151 to the display element 110 and lost via displayelement 110 and focusing element 160).

When IR light 162, 163 strikes an IR sensor 172, a signal 173 isgenerated that is received and processed by a light source driver 174(one provided per sensor 172). The driver 174 is configured to triggeroperation as shown at 175 of one (or more) of the light sources 176paired with or associated with the IR sensor 172 that sensed/receivedthe IR light 162, 163. As with the IR sensors 172, the light sources(e.g., a white LED or the like) 176 are arranged in tiered rows. In someembodiments, the light sources 176 are each a high illumination, whiteLED that has its operation triggered by sensing of IR 162, 163 by asensor 172. The LED 178 may be positioned immediately adjacent (e.g.,within 1 to 2 inches with some configurations placing a row of LEDswithin 0.5 inches from a row of associated IR sensors) to the sensor172. Such close positioning is used such that the generated light 178,179 retraces the optical path followed by IR 162, 163 to the focusingelement 160 for return to the eye 106, 107 as left and right eye images115, 117.

As shown, receipt of left eye IR 162 is sensed by an IR sensor 172, anda driver 174 operates a light source 176 paired to the IR sensor 172 togenerate left eye light 178 (e.g., white light). The left eye light 178strikes focusing element 160 which focuses or directs the light 178through the displaying element 110. This acts to back light the displayelement 110 such that (due to synchronization of signals 127 and 136)the left eye image 114 is visible on display surface 112 as light orleft eye image 115 travels along the same (or a similar) path asreflected left eye IR 150 to reach the left eye 106 of the viewer 105.

Then, similarly, when the controller 120 switches to the right eyeimages 125, an IR sensor 172 senses right eye IR 163. In response, asignal 173 is provided to driver 174, which operates as shown at 175 alight source 176 to produce right eye light 179. The right eye light 179originates from a location nearly identical to the IR sensor 172 pairedwith the light source 176 such that the light 179 strikes the focusingelement 160 and is focused through the display element 110 onto theright eye 107 of the viewer 105. In other words, in this secondoperating time period, the right eye image 116 is backlit by the backlight assembly 170, and a right image or light 117 associated with image116 is transmitted along an optical path matching the path of reflectedright eye IR 151 through the viewing space 102 to reach the right eye107 of the viewer 105.

This operation or switching between right and left eye images (andoperation of right and left IR light sources 141, 140) is repeated on anongoing basis to provide a 3D viewing experience for viewer 105 withoutthe need for special glasses and without requiring the viewer 105 tohold their head still as head orientation and eye location is indicatedby the optical path of the reflected right and left eye IR 150, 151throughout operation of the 3D display 100.

FIG. 2 illustrates a 3D display system 200 that is being operated todeliver 3D images to a viewer or audience member 205. The viewer 205 isshown to be standing in a viewing space 202, but, more typically, theviewer 205 would be positioned in an individual seat in one of a numberof tiered rows (as in a theater or amusement park vehicle). The viewingspace 202 is in front of a LC display 210, and each viewer 205 (oneshown for convenience but more typically the system 200 would be usedfor 2 to 20 or more viewers) is in one of a number of predefined viewingpositions. More accurately, their head is within one of a number oflocations (e.g., viewing spaces or volumes that may be called “headboxes”). In this way, invisible light such as IR light can be used toilluminate the left and right sides of their faces in an alternatingmanner (time-multiplexed illumination that is synchronized to left andright image displaying on LC display 210).

In this regard, the system 200 includes a pair of collimated IRilluminator assemblies 240, 241. The first assembly 240 is used toilluminate the left side of the face of the viewer 205 with collimatedIR as shown at 246 (and her left eye 206) while the second assembly 241is used to illuminate the right side of the face of the viewer 205 withcollimated IR as shown at 247. Again, the left or first assembly 240 isoperated when left eye images are shown on LC display 210 and the rightor second assembly 241 is operated when right eye images are shown on LCdisplay 210.

Each assembly 240, 241 is configured with a number of IR light sources(as shown at 243 for assembly 241) arranged to illuminate the viewingpositions (and viewers 205) positioned between the assemblies 240, 241.For example, a theater row of seats may be positioned between theassemblies 240, 241 (e.g., the assemblies 240, 241 may be mounted on theside walls of the theater or ride vehicle), and the row may include fourindividual seats. In this example (as shown), the assembly 241 (and 240,too) may include a number of IR illuminators 243 (e.g., an IR emitterpaired with a collimator element), the group being angled so as to causethe IR light to project onto a more contiguous surface area such as amore rectangular area arranged vertically on end to illuminate aviewer's face with the viewer's head positioned at a range of viewingheights while in a particular seat of a row).

Alternatively, individual, and smaller, IR light sources can be mountedat the left and right sides of each individual seat position, e.g., aspart of a head bolster. This bolster can be designed to be adjustable inheight so as to adjustably light the left and right side of eachaudience member's face. These individual seat lights can still beinterconnected so that all left side illuminators are illuminated whenthe left side image is displayed on display element 110 and so that allright side illuminators are illuminated when the right side image isdisplayed on display element 110.

As shown, illuminators of the left assembly 240 are presently beingoperated to provide IR light 246 that strikes and illuminates the leftside of the face of the viewer 205 (including her eye 206). At thistime, the assembly 241 would be turned off or not be projecting IR 247(as only one of the assemblies 240, 241 is operated at a time in the 3Ddisplay system 200). A portion of this IR 246 is reflected as shown at250 towards the LC display 210. The LC display 210 is transparent (or atleast mostly transparent) to the IR 250 such that this light strikes theFresnel lens 260, which is separated by a small distance, d_(Lens), ofless than about 6 inches or abuts the back side of LC display 210. TheFresnel lens 260 typically is the same shape and size of the LC display210 to receive all of the light 250.

The 3D display system 200 also includes a light bar 270 positioned adistance, d_(Back Light), behind the LC display 210 (opposite theviewing space 202). The distance, d_(Back Light), is chosen based on theconfiguration/design of the lens 260 and the distance to the viewer 205such that the focused IR light 262 is directed onto the light bar 270.In other words, the light bar behind the LC screen and lens is in aposition conjugate to viewer's head positions in front of the LC screen.As with the assemblies 240, 241, the number of light bars 270 is chosento match the number of viewing rows in the theater/vehicle ride (orother viewing space) 202. For example, if there are 3 rows in theviewing space 202, the 3D display system 200 will include 3 of the lightbars 270 (with their distance and height relative to the LC display 210and lens 260 chosen to cause the focused IR light 262 to strike a lightbar 270 paired with a row of viewers/viewing locations). The focusing ofthe lens 260 may allow the light bar 270 to be closer to the LC display210 than the viewer 205, and the distance, d_(Back Light), will vary tosuit the viewing distance of the viewer 205 as well as the lens 260(e.g., the distance, d_(Back Light), may be one fourth to one tenth orless than that of the viewing distance to the viewer 205). In order tomore finely place each IR/visible light couple at the conjugate positionto viewers in front of the system, the entire light bar may be curved(not shown in the figures but readily understood by those skilled in theoptical/display arts) to match the Petzval focusing surface of thefocusing element used.

The light bar 270 includes a row of IR receivers (detectors or sensors)that are each used to trigger operation of a visible light emitter(e.g., a white LED or the like). Hence, as shown, the light 262 isfocused by the lens 260 onto the light bar 270, which functions torespond by generating light 278 (e.g., white light) at about thelocation where the IR light 262 struck the light bar 270. This visiblelight 278 returns along the path of the focused IR light 262 to the lens260, which focuses it through the LC display 210, which acts to backlight it and display a left eye image (in this operating example ofsystem 200). The left eye image 250 (or light “carrying” thisdata/image) is focused by the lens 260 onto the face of the viewer 205so that it is perceived or received by the left eye 206 of the viewer205. In this way, the display system 200 operates at a first time toilluminate the left side of the viewer's face with IR 246, and thiscauses the left eye image 250 to be nearly instantaneously provided tothe viewer 205 at the present location of their left eye 206.

FIG. 2 illustrates a 3D display system 200 with a simple, one rowviewing space for viewers in four spaces between two illuminatorassemblies. In contrast, FIG. 3 shows a 3D display system 300 configuredfor use with three tiered rows of seats, with the seats not specificallyshown but these or other viewer positioning devices being used toposition the viewers whose heads are shown.

Particularly, the 3D display system 300 has a viewing space or volume302 in front of a display or front surface of a 3D display device 310such as a transparent LC display (an LCD monitor with at least the backlight portion removed). A number of viewers are shown in the displayspace 302, and viewers 305 and 306 are in a first, lower row 390 with afirst viewing distance, Viewing Distance 1, as measured from the LCdisplay 310 to the viewer's head/eye locations. The viewers 305, 306 arealso at a first viewing height, Viewing Height 1, relative to the spacefloor or a horizontal reference plane 303. Viewer 307 is in a second andhigher row 392 with a second viewing distance, Viewing Distance 2, thatis larger than the first viewing distance and with a second viewingheight, Viewing Height 2, that is greater than the first viewing height.Further, viewer 308 is in a third and still higher row 394 with a thirdviewing distance, Viewing Distance 3, that is larger than both the firstand second viewing distances and with a third viewing height, ViewingHeight 3, that is larger than the first and second viewing heights. Inthis way, the viewers 305, 306, 307, 308 are placed in individual andpredefined viewing locations in one of three tiered rows 390, 392, 394.Light bars are generally placed optically conjugate to these viewingpositions behind the LC screen and Fresnel lens.

The rows 390, 392, 394 are each located between a pair of sideilluminator assemblies that are used to selectively wash the left andright sides of the viewer's faces with invisible, IR light, which issynchronized with display of left and right images on the LC display310. For example, the first row 390 is IR illuminated by left and rightilluminator assemblies 342, 343, which each includes an IR source andcollimator that is targeted/focused so as to emit IR over an areaassociated with a viewer's head (left and right sides of their facessuch as faces of viewers 305, 306). The second row 392 is IR illuminatedby left and right illuminator assemblies 344, 345 to illuminate the leftand right sides of the face of viewer 307 (with assembly 345 shown toinclude 4 illuminators which may be useful if each row 390, 392, 394includes 4 seats but fewer or greater numbers may be used to suit thenumber of seats in a row). The third row 394 is IR illuminated by leftand right illuminator assemblies 348, 349 to illuminate the left andright sides of the face of the viewer 308.

During operation of system 300, the left assemblies 342, 344, 348 areoperated concurrently when a left eye image is displayed on LC display310 and the right assemblies 343, 345, 349 are operated concurrentlywhen a right eye image is displayed on LC display 310. This results inthe reflected IR from all the left sides of the viewers' faces strikingthe LC display 310 concurrently (and the LC display 310 to be back litby light bars to return the left eye images to the viewers) and thereflected IR from all the right sides of the viewers' faces striking theLC display 310 concurrently (and the LC display 310 to be back lit bylight bars to return the right eye images to the viewers).

FIG. 3 shows operation of the system 300 at a first time when a left eyeimage is being displayed on the LC display 310. At this time, the leftassemblies 342, 344, 348 are each operated to provide IR light on theleft side of the viewer's faces (as discussed with reference to FIGS. 1and 2). As shown for viewer 305, this results in reflected IR 350 beingdirected onto the LC display 310, which is transparent to IR light suchthat it passes through to strike Fresnel lens (or other lens) 360. Thelens 360 acts to focus the reflected IR light as shown at 362 into aback light assembly 370.

The back light assembly 370 includes a set/assembly 372 of tiered lightbars 373, 374, 375 that are arranged in a predefined and/orexperiment-proven arrangement and positions so as to receive the IRlight 362 from the lens 360. Particularly, the back or third row 373 ispositioned to receive the light from faces/viewers 305, 306 in the firstrow 390, the middle or second row 374 is positioned to receive the lightfrom faces/viewers 307 in the second row 392, and the front or first row375 is positioned to receive the light from faces/viewers 308 in thethird row 394. The rows of light bars 373, 374, 375 are tiered to be atdiffering heights and distances from the back of the LC display 310 andlens 360 (but with a conjugate arrangement).

As shown in FIG. 3, light 350 reflected from the front row viewer 305 isfocused as light 362 onto an IR detector in the third or back row 373.This results in a white or visible light source in the light bar 373being activated to emit light 378 back towards the lens 360 and LCdisplay 310 (along substantially the same optical path(s)). A verticaldiffuser 376 is provided between the light bars 373, 374, 375 and thelens 360 such that the light from each light source on the light bars373, 374, 375 is stretched or diffused in the vertical direction, and,as discussed above, this is useful to allow light from a point source tobe made to fill a larger vertical area when the light reaches the rows390, 392, 394 in the viewing space 302, e.g., to provide light“carrying” a left or right eye image to strike a vertical dimension of ahead box/viewer eye position range. For example, the light may bediffused by vertical diffuser 376 to provide a vertical band of light(image 315) that is between 6 and 24 inches when it reaches the viewers'eyes.

The diffused IR light 378 strikes the lens 360 and is focused throughthe back of the LC display 310. This causes the LC display 310 to, inturn, be back lit through the action of the light bar, and, because theoperation of the illuminator assembly 342 is synchronized with displayof a left eye image on LC display 310, the light 315 illuminates theleft side of the face of the viewer 305 with a left eye image. In thisway, the left eye of the viewer 305 receives a left eye image during theoperating state of system 300 shown in FIG. 3. Although not shown forease of description, viewers 306, 307, 308 would concurrently bereceiving a left eye image from display 310, but along differing opticalpaths as the IR light reflected from their faces would define uniqueoptical paths for return of back lighting from the back light assembly370. In other words, the reflected light from each of the viewer's facescauses differing ones of the IR detectors of light bars 373, 374, 375 tosense IR light and trigger operation of differing ones of theLEDs/visible light sources to provide back lighting 378. This differingback lighting 378 is focused by lens 360 to return back to each vieweralong the paths of the reflected IR light 350 and back to their lefteyes (in the example of FIG. 3).

FIG. 4 illustrates the 3D display system 300 during the same operatingstate as in FIG. 3 to deliver a left eye image to a different viewer.Particularly, while the viewer 305 is presented a left eye image 350 asshown in FIG. 3, the viewer 308 in the back or third row 394 alsoreceives a left eye image 315. To this end, the left illuminatorassembly 348 is operated to wash the left side of the face of the viewer308 with invisible IR light (e.g., with an IR LED and a collimator).

The reflected IR 350 at least partially reaches the front/displaysurface of the LC display 310 and passes through this IR-transmissivematerial/element. The lens 360 focuses the IR light 362 onto the frontor first light bar 375 in the back light assembly 370, e.g., the backrow 394 focuses its IR light onto the front row 375 of the light bars370. One or more detectors of IR generates an output signal that adriver or other device uses to trigger operation of a paired visiblelight emitter (e.g., a bright white LED or the like), and visible light378 is emitted back along the same optical path(s) as the focused IRlight 362. The lens 360 receives this visible (e.g., white) light 378and focuses it through the LC display 310 (or back lights the LCdisplay), and this causes the presently displayed left eye image to bedirected with light 315 onto the left eye of the viewer 308. In thisway, IR light striking the viewer's face on or near their left eyetriggers display of a left eye image via light from a back lightingsource in light bar 375 in a manner that causes light 315 to travel totheir left eye (and not their right eye or to any other viewers' eyes).

FIG. 5 is intended to show the operation of the 3D display system 300 toconcurrently deliver left eye imagery 315 to each of the audiencemembers or viewers 305, 306, 307, 308. Each receives their own left eyeimage light stream 315 in response to their faces reflecting IR light350 onto the LC display 310. The lens 360 concurrently focused thesevarious light streams 350 onto differing ones of the tiered light bars373, 374, 375, which causes differing ones of the IR detectors/sensorsto sense the light 362 from each viewer 305, 306, 307, 308 and triggeroperation of a paired LED or other visible light source. Light 378travels from each of these point light sources on bars 373, 374, 375 tothe viewers 305, 306, 307, 308 via lens 360 and LC display 310 as shownwith rays 315 (which provide left eye images shown on LC display 310 ina manner that is synchronized with operation of the left illuminatorassemblies 342, 344, 346). In this way, a viewer may sit in any row 390,392, 394 of the viewing space 302 and view a 3D show.

While not shown, the right illuminator assemblies 343, 345, 347 would beoperated concurrently with each other and in a manner that is timesynchronized with operation of the LC display 310 to display right eyeimages. In other words, the left illuminator assemblies 342, 344, 346would be operated in a first time slot/period followed by the rightilluminator assemblies 343, 345, 347 being operated in a second timeslot/period. This pattern would be repeated as would operation of the LCdisplay 310 to show a 3D image stream by showing images for viewing bythe left eye, the right eye, the left eye, the right eye, and so on.

The light bars 373, 374, 375 of system 300 may be implemented in anumber of ways. For example, but not as a limitation, FIG. 6 illustratesa perspective view of one useful light bar 670 that may be used toprovide the functionality of a light bar of a back light assembly in a3D display system. The light bar 670 includes a base or body 672 that isused for supporting or mounting a detector/sensor row 680 and a lightsource/emitter row 690.

The two rows 680, 690 are linear as shown with lines 685, 687 extendingalong the lengths of the two rows 680, 690 (such as through centerpoints of IR receivers 682 and of white light emitters 692), and the tworows 680, 690 are parallel to each other on the base/body 672. The tworows 680, 690 are spaced apart a relatively small distance, d₂, asmeasured between center points of paired devices 682, 692 or lines 685,687, so that, when light is received by a receiver 682, a paired oradjacent emitter 692 emits visible light (e.g., white light) from nearlythe same location on the light bar 670 (or body 672). In this way, thelight from the emitter 692 returns to the source of the received IRlight or to a viewer's face and, particularly, to their left or righteye.

The side spacing, d₁, between side-by-side receivers 682 and betweenside-by-side emitters 692 (as measured between two lines 681, 683passing through the center of the devices) is also minimized or keptrelatively small. In this way, any IR striking the light bar 670 is morelikely to strike a receiver 682 in the row 680. This close spacing, d₁,(e.g., less than 0.5 inches and more typically less than 0.25 inches)allows the viewer to move their head side-to-side in their seat whilestill having a receiver 682 available and in the correct position on thelight bar 670 to receive IR reflected from their face (i.e., the lightbar 670 is not only configured for receiving reflected IR from a row ofviewing positions but also the viewing positions each may have ahorizontal range (such as 12 to 24 inches per viewer or the like).

The IR receivers 682 may take the form of off-the-shelfsensors/detectors such of the type of infrared receivers often used inLCD and other television monitors. These may be specially suited to beparticularly sensitive for IR that is within a predefined frequencyrange. With this in mind, a prototype of the light bar 670 uses IRdetectors 682 that are configured for detecting a 38 kHz modulatedsignal (but other frequencies may be used), and the IR source in theside illuminators placed in the viewing space are controlled toilluminate viewers' faces with IR modulated at 38 kHz. In way, the IRsensors 682 may require significantly less power, may be inexpensive toobtain (e.g., use an existing standard), and provide highly robustdetection of the reflected IR light striking the light bar 670 on row680.

Likewise, the white light emitters 692 may generally be any deviceuseful for providing visible light rapidly (in response to an outputsignal from an IR detector 682) and at high illumination levels (toproperly back light an LC display). To this end, bright white LEDs maybe used to provide point sources 692 of visible light at or nearly atthe location of a particular IR detector 682. Alternatively (not shown),the white light emitters may be vertically stacked (from the plane ofthe light bar) multicolored LEDs. For instance red, green and blue LEDswith substantially transparent cases may be stacked with the blue LEDclosest to the Fresnel lens and viewer and the red LED furthest from theFresnel lens and viewer, with the green LED centered between them. Thiscan be done to compensate for chromatic aberration in a Fresnel lenssince shorter wavelength light will focus closer to the LED group andlonger wavelength light further from the LED group.

In FIG. 6, the light bar 670 is configured such that the front receivingand emitting surface, respectively, of the IR detector 682 and the lightemitter 692 are coplanar. This may be useful in some applications. Inother cases, though, it was recognized by the inventors that thereflected IR light was focusing behind the visible light such that itmay be useful to adjust the heights of the IR sensors (or the lightemitters) so as to place the receiving surfaces of the IR detectorsfurther away from the focusing lens than the visible light emitters.

With this differing focal length of the IR and visible light streams inmind, FIG. 7 shows a light bar 770 in which the receiving and emittingsurfaces are not coplanar and are spaced apart relative to the base 772.As shown, the light bar 770 includes a base or body 772 on which ismounted a row 780 of infrared receivers 782 and a parallel row 790 ofvisible light emitters 792 (e.g., white LEDs or the like). The receivingsurfaces of the receivers 782 are shown to be closer to the base 772than the emitting surfaces of the emitters 792 such that any received IRhas to travel farther to reach the light bar 770 than light emitted fromthe emitters 792 to strike a Fresnel or other lens and the LC display.To this end, the plane containing the detecting or receiving surfaces ofthe IR detectors 782 is an offset distance, d₃, from the planecontaining the emitting surfaces of the emitters 792, and this offsetdistance, d₃, is determined by calculating the differential focusingdistance between infrared and visible light and to suit the relativedistance of the viewers/viewing location in the viewing space to thefocusing element/LC display but may be in the range of 0.1 to 1 inch inmany applications.

As discussed earlier, the operation of a 3D display system can beenhanced by conditioning the light used to back light an LC display soas to better illuminate a viewer's face (and their left and right eyes)with 3D images. More specifically, the components utilized in a lightbar to provide visible light may be point sources such as white orother-colored LEDs. If no conditioning is performed, the left or righteye image displayed into the viewing space by these sources may beprovided on a relatively small area (with an area of less than a squareinch in some cases), which can make it difficult to ensure that aviewer's eye receives the light and its associated left or right eyeimage.

With this in mind, the inventors recognized that it may be useful toinclude at least one vertical diffuser to provide spreading of thevisible light in the vertical direction and a weak isotropic scattererto prevent dark areas as the viewer's head, and eyes, move left andright and thus would move into, and out of, areas lit by the pointsource bright white emitters in conjugate space in a light bar.Additionally, the horizontal diffuser's slight scattering in alldirections also evenly distributes visible light so that the pointsource nature of the white light LEDs does not translate into unevennessin the overall appearance of the image on the LC display. The horizontaldiffuser is preferably only placed over the bright light emitters so asnot to dull the horizontal detection accuracy of the infrared receiverson the light bar.

The vertical diffuser provides vertical-only expansion of the light raybundle leaving the LED while not affecting lateral accuracy. Using thesetwo light processing elements, the viewing area for each eye at eachseat (or other viewer positioning device) can be made large enough(e.g., 6 to 20 inches vertical) but is preferably kept small enough inwidth that it does not wash onto the viewer's other eye, e.g., imagesintended for the left eye do not also strike the right eye, and, hence,more vertical diffusion is typically provided than horizontal andisotropic scattering.

FIG. 8 illustrates a portion of a back light assembly using light bar770 with the IR receivers 782 offset from the light emitters 792. Theback light assembly further includes a horizontal diffuser (or isotropicscatterer) 894 that is positioned adjacent the row 790 of light emitters792. The diffuser 894 may take the form of a narrow rectangle with alength exceeding the length of the row 790 to cover all the emitters 790and a relatively small width chosen based on the emitters 792 so as tocover the emitters 792 but not cover the IR receivers/detectors 782.Spaced apart a distance, d₄, (such as 2 to 8 (or more) inches) from theisotropic scatterer 894 is a vertical diffusing sheet or verticaldiffuser 898. Again, the diffuser 898 may take the form of a rectanglewith a length chosen based on the length of the row 790 and also on thedistance, d₄, and vertical diffuser 894 such that all (or most) of thelight passing through the horizontal diffuser 894 passes through thevertical diffuser 898 (and then onto the focusing element such as aFresnel lens). The use of the vertical diffuser 898 allows the height ofthe viewer to vary and provides some vertical tolerance to a 3D displaywhile the horizontal diffuser provides some horizontal tolerance butalso conditions the light to allow a point source such as an LED to actas a back light for a large LC display.

FIG. 8 shows use of one light bar in a back light assembly as may beuseful to serve a single row of viewers. More typically, though, theviewing space will be arranged to contain two, three, or more tiered(differing viewing heights and viewing distances) rows as is common in amovie theater or similar 3D viewing application. With this in mind, FIG.9 illustrates a back light assembly 900 that may be used in a theater orother viewing space with three tiered rows of one to many seats(individual viewing locations).

In the assembly 900, the light bar 770 is provided as a first or upperlight bar paired with the horizontal diffuser 894. Further, the assembly900 includes a similarly configured second or intermediate-height lightbar 970 (with a horizontal diffuser such as that shown at 894) and alsoincludes a similarly configured third or lower light bar 972. The lowerlight bar 972 is used to serve an upper row in a viewing space (as thelight is focused in a conjugate manner) and is positioned at a first(lowest) height, h₁, relative to a reference plane 901 (as measured to aline passing through the centers of the light emitters (or theiroutlets)). The intermediate light bar 970 is used to serve a middle orintermediate height row in the viewing space and is positioned at asecond (middle) height, h₂, relative to the reference plane 901.Further, the upper light bar 770 is used to serve a lower row of viewersin the viewing space and is positioned at a third (highest) height, h₃,relative to the reference plane 901.

The heights of the rows 770, 970, and 972 are chosen to suit the amountof tiering (or differences in the row heights) in the viewing space andalso based on the configuration of the lens. To cause the reflected andfocused IR light to strike the rows of IR receivers (such as detectors782) on each light bar 770, 970, 972, each row is set at one of threedistances from the focusing lens and LC display (not shown in FIG. 9).This is shown with the intermediate row 970 set back a distance, d₅,from the front/lower row 972 and the upper or third row set back adistance, d₆, from the intermediate or second row 970.

These offset distances, d₅ and d₆, may be equal and, again, are chosento suit the viewing distances defined for viewers in the viewing spaceby the tiered rows of seats. Three horizontal diffusers (such asdiffuser 894) are included in the back light assembly 900 to spread theoutput visible light in the horizontal direction, and, in thisembodiment, one vertical diffusing sheet (or diffuser) 898 is used tospread the output visible light from all three of the light bars 770,970, and 972 in the vertical direction (e.g., to account for varyingheights of viewers that may sit in each viewing location in the viewingspace (e.g., 3D theater or ride vehicle)).

FIGS. 10A to 10C illustrate three schematic representations of a portionof a light bar showing differing approaches for detecting IR andtriggering back lighting of an LC display. Particularly, FIG. 10A showsthat for a light bar 1010 each IR receiver 1012 is paired with onevisible light emitter 1018. As shown, IR light 1014 strikes the lightbar on the IR receiver 1012, which may take the form of an IRphototransistor that is configured to respond to receipt of the IR 1014by outputting a signal 1013 to a driver circuit 1016. The driver circuit1016 processes or conditions the signal 1013 to generate a controlsignal 1017 expected by a visible light emitter 1018, which may take theform of a white light LED, that responds to the signal 1017 to emitvisible light onto an LC display (via a focusing element). In thismanner, there is substantially no lag between receipt of the reflectedand focused IR 1014 and emitting the visible (white or other colored)light 1019.

FIG. 10B shows a light bar 1020 showing a hardware implementation thatmay be used to drive the light emitter. As shown, an IR receiver 1022 isconfigured to output a voltage signal upon receipt of IR 1024 to adriver 1026, which triggers operation of a visible light LED 1028 toemit light 1029. One issue with the light bar 1020 is that it mayrequire relatively high levels of incoming IR 1024 to trigger theoperation of the LED 1028. So, it may be desirable in some applicationsto provide a highly sensitive IR detector such that much lower levels ofIR are needed to illuminate viewers' faces in the viewing space totrigger back lighting by visible light emitters.

To this end, FIG. 10C shows a light bar 1030 in which an IR receiver1032 is used to receive and provide an output signal to driver 1036. TheIR receiver 1032 is configured to receive IR that is modulated to aparticular frequency or range of frequencies. For example, manytelevisions utilize IR receivers that are adapted for detecting 38 kHzmodulated IR, and, since this is a standard, much work in the televisionindustry has been performed to make such IR receivers very sensitive torelatively low amounts of IR (such as from a remote for a television).Hence, the light bar 1030 may use an IR receiver 1032 in the form of aconventional 38 kHz IR receiver (such as the Model TSSP4038 from VishayInc.), and the levels of IR 1034 required to trigger operation of thedriver 1036 are reduced. When even small amounts of IR 1034 arereceived, the receiver 1032 sends a control voltage/signal to the driver1036, which responds by triggering operation of the white orother-colored LED 1038 to emit light 1039 to a focusing element and anLC display.

A low pass filter (not shown) may be placed between the receiver 1032and drive transistor 1036 with a cut off frequency sufficient to passthe left-right frame transition frequency but not the 38 kHz signal tothe white light emitter thus preventing any possibility of feedback of38 kHz white light to infrared receiver 1032. Although this path ishighly attenuated, it can cause local oscillations due to the proximityof the IR receivers 1032 and white light emitters 1039.

Each of the circuits described in FIG. 10 provide substantiallyminiscule amounts of delay between the times that IR energy is reflectedfrom a viewer's face and the times bright illuminating imagery from theLC screen is returned to their face so that the system effectivelyperforms instantaneous head tracking.

As discussed above, a 3D display system is operated such that the leftportion of a viewer's face is illuminated with IR while a left eye imageis displayed and such that the right portion of the viewer's face isilluminated with IR while a right eye image is displayed. With this inmind, it is desirable that the 3D display system include one or moredevices for providing time synchronization between the LC display (orother display element) and the illuminators. FIG. 11 illustrates a 3Ddisplay system 1100 (or a portion of one) that uses the synchronizedoperation of shutter glasses to control the illuminators. Briefly, a 3Dtelevision may operate by synchronizing the opening and closing of apair of shuttered lens in a viewer's glasses with display of left andright eye image, and this controlled shuttering likewise be used tocontrol selective illumination of the viewer's left and right eyes (orthe sides of their face).

To this end, the system 1100 includes rows of left collimatedilluminators 1140 for generating IR 1141 to illuminate the left sides ofviewers' faces with the viewers in tiered rows and further includesright collimated illuminators 1150 for generating IR 1151 to illuminatethe right sides of viewers' faces. A sync generator 1110 is providedthat includes a white light emitter (LED or the like) 1114 directed at aleft eye glass 1112 and a white light emitter (LED or the like) 1115directed at a right eye glass 1113.

The emitters 1114 and 1115 operate on an ongoing basis to emit light1116 and 1117, but the left eye glass 1112 and the right eye glass 1113are shuttered (not shown) such that one of the two glasses 1112, 1113 isopen at any particular time. More specifically, the left eye glass 1112has its shutter opened when a left eye image is being displayed on an LCdisplay and the right eye glass 1113 has its shutter opened when a righteye image is being displayed (and each is closed when the other eyeimage is being displayed). The control over the glasses 1112, 1113 canbe provided by a conventional shuttered glasses 3D television system(and may be used as display controller 120 and/or system controller 130of system 100 in FIG. 1).

When a shutter is open, light 1118 or 1119 passes through a lens/glass1112, 1113 to strike a light detector 1120, 1121. The detectors 1120,1121 respond by triggering operation of a pulse timing device 1122, 1123to provide a control signal to the left collimated illuminators 1140 toilluminate the left sides of viewers' faces or to the right collimatedilluminators 1150 to illuminate the right sides of viewers' faces. Inthis way, each viewer has the left side of their face (and left eye)illuminated when the left eye glass 1112 is open and has the right sideof their face (and right eye) illuminated when the right eye glass 1113is open. This acts to synchronize in time the display of left eye imageson a display with reflection of IR off of a viewer's left side and thedisplay of right eye images on a display with reflection of IR off of aviewer's right side.

The 3D display system 1100 further includes a signal modulator 1130linked to the left and right collimated illuminators 1140, 1150. Asdiscussed above, the use of a particular modulated frequency can be usedto provide much more sensitive IR receivers. A present standard for anIR receiver is 38 kHz, and the modulator 1130 may function to cause theIR 1141, 1151 provided by the illuminators 1140, 1150 to be modulated at38 kHz to match the IR receivers of one or more light bars in a backlighting assembly (not shown in FIG. 11).

To this point in the description, 3D display systems have been discussedthat use IR detectors paired with LEDs or other point sources of lightor that use a particular lens or display element. However, it will beapparent to one skilled in the arts that once the general concepts for3D display systems taught herein are understood that a wide variety ofcomponents may be used to create a 3D display system that functions toprovide a 3D experience to a viewer without the need for special glassesor headgear. With this in mind, the following discussion describes anumber of 3D display systems that may use some of the componentsdiscussed above (and for which like numbering is used and which are notdiscussed again in detail such as illuminators 240, 241) but thatreplace one or more devices to create unique 3D displays.

FIG. 12 illustrates a 3D display system 1200 similar to system 200 ofFIG. 2 that is adapted with a different back light assembly 1270.Particularly, the assembly 1270 includes an IR camera 1274 thatfunctions to receive IR light 1273 that is focused by the Fresnel lens260 onto a diffusing screen 1272. The assembly 1270 further includes avideo-to-linear light bar converter 1280 that processes the outputsignal/data from the IR camera 1274 to provide control signals 1281 tooperate LEDs or other light sources arranged in a linear row on a lightbar 1290. The light bar 1290 responds by emitting visible light 1294that is focused by lens 260 through LC display 210 to viewers 205positioned between collimators 240, 241. In this manner, individual IRreceivers are not required for each visible light source and “IRdetector/receiver” can be understood more broadly to include any devicecapable of detecting IR and “driver” can be any device used to triggeroperation of particular ones of the LED/sources of a light bar (such aslight bar 1290).

FIG. 13 illustrates a 3D display system 1300 similar to system 200 ofFIG. 2 and system 1200 of FIG. 12 using a different back light assembly1370. In the back light assembly 1370, an IR camera 1374 is providedadjacent and/or in front of the LC display 210 (or in the viewingspace). The IR camera 1374 provides a signal/data 1378 that provideslive tracking of IR light in the viewing space in front of the LCdisplay 210 such as IR being reflected from the left and right sides ofthe face of the viewer 205. A converter 1380 is provided in the backlight assembly 1370 that functions to generate an LED array controlsignal 1381 based on the video signal 1378 or to provide videoraster-to-LED array conversion to selectively operate the LEDs in a LEDlight bar 1390 to illuminate the LC display 210 via lens 260. The lightbar 1390 may include one or more rows of LEDs that can be independentlyoperated by converter 1380 with signal 1381 to direct IR light throughthe display 210 onto a left or right side of a face of a viewer 205positioned between illuminators 240, 241.

FIG. 14 illustrates a 3D display system 1400 similar to that of system200 of FIG. 2 in which a different back light assembly 1470 is used toback light the LC display 210. As shown, a cylindrical or curvedreflector 1472 is placed behind the LC display 210 (opposite the viewingspace where illuminators 240, 241 are placed). The reflector 1472 mayinclude a vertical diffuser spaced apart or on the reflector'sreceiving/reflecting surface. IR light is provided by the illuminators240, 241 and reflects off the left and right sides of the face of viewer205. This light travels through the IR-transparent display 210 and ishorizontally focused and vertically reflected by the cylindricalreflector 1472.

The reflector 1472 along with the vertical diffuser reflects and focusesslightly vertically-diffused IR light to strike the light bar 1490,which may be configured as shown in FIG. 6 or 7 with an IR receiverpaired with a visible light emitter. Hence, the IR light causes thelight bar 1490, which is facing away from the LC display 210 towards thereflector 1472, to emit visible light from point sources. This visiblelight reaches the reflector 1472 and is reflected (horizontally focusedand slightly vertically diffused) back through the LC display (toprovide back lighting while left or right images are displayed) and ontothe viewer 205. As with the other 3D displays, in the system 1400, thelight bar 1490 acts to provide light for back lighting the LC display210 for each eye of each viewer 205 as the light returns along the pathdefined by the reflected IR light from the left and right sides of theface of viewer 205 originating with illuminators 240, 241.

FIG. 14A illustrates a 3D display system 1400A similar to the system1400 of FIG. 14. However, in system 1400A, a horizontal, cylindricalFresnel lens 1460 is used and is mounted adjacent to the LC display 210.The horizontal focus is provided by the cylindrical reflector 1472A(shown without a vertical diffuser), while vertical focusing (which maybe somewhat weaker power) in the system 1400A is provided by thehorizontal linear Fresnel lens 1460.

FIG. 15 shows a 3D display system 1500 similar to system 200 of FIG. 2and system 1400 of FIG. 14 but with a modified or different back lightassembly 1500. As shown, the back light assembly 1570 includes a lightbar (one to many rows of pairs of IR receivers and visible lightemitters) 1590 that faces away from the LC display 210. IR light fromthe illuminators 240, 241 is reflected off of the sides of the face ofviewer 205 passes through the LC display 210 and is focused by thereflector 1570 with vertical diffuser toward light bar 1590.

Spherical reflector 1572 is spaced apart a focal distance from the LC210. This distance is chosen such that the focused IR light is reflectedonto IR receivers of the light bar 1590 and also such that light emittedby emitters of the light bar 1590 striking the reflector 1572 returns onthe same/similar path through the LC display 210 and out to the left orright eye of the viewer 205. The reflector 1572 may be covered with avertical diffuser (or one may be positioned between the reflector 1572and LC display 210) to spread the reflected visible light verticallyprior to it being delivered to the viewer 205.

In an alternate embodiment, the switching between left and right eyeimages for viewers may be achieved through the use of polarized lightand switching between vertical and horizontal polarization of light usedto back light an LC display. For example, FIG. 16 illustrates a 3Ddisplay system 1600 similar to that of system 200 in FIG. 2 but with apolarization-based back light assembly 1670. The back light assembly1670 includes a light bar 1690 that selectively provides visible light(e.g., white light) in response to the IR from the illuminators 240, 241striking the viewer 205 and reflecting through the LC display 210 andbeing focused by the Fresnel lens 260. The back light assembly 1670 (ordisplay assembly including LC display 210) includes a patternedpolarizer 1672 and a screen-sized polarization rotator 1674 sandwichedbetween the display 210 and the Fresnel lens 260.

The illuminators 240, 241 are synchronized to operate with thepolarization rotator 1674 such that the left illuminator 240 operateswhen the rotator 1674 is operated to polarize the light from light bar1690 to show left eye images with display 210 and further such that theright illuminator 241 operates when the rotator 1674 is operated topolarize the light from the light bar 1690 to show right eye images withdisplay 210. For example, a sync signal 1675 is provided to thepolarization rotator 1674 to switch between vertical and horizontalpolarization of the light from light bar 1690 to show first left andthen right eye images with display 210, and the left and rightcollimators 240, 241 will be synchronized to operate with the rotator1674 to illuminate the left and right sides of the face of the viewer205 (and other viewers in the viewing space) with display of the leftand right images.

In FIG. 17, a 3D display system 1700 is shown that is similar to thesystem 1600 of FIG. 16 but with a somewhat different arrangement in theback light assembly 1770. Particularly, a patterned polarizer 1772 isplaced between the LC display 210 and the lens 260. However, theswitched polarization rotator 1774 is placed between the lens 260 and alight bar (or bars) 1790. Typically, the rotator 1774 will be placedproximate (such as several inches or less from) the light bar 1790 suchthat its size can be minimized while still conditioning the emittedwhite (or other colored) light from the light bar 1790. As with thesystem 1600, the operation of the rotator 1774 is synchronized using async signal 1775 from a controller, and a similar signal would be usedto operate the left and right illuminators 240, 241 (left illuminationwith IR concurrently with polarization to show left eye images and viceversa).

FIG. 18 shows another 3D display system 1800 in which the rightcollimated IR illuminators 241 are operated 1843 to provide IR with afirst digital code while the right collimated IR illuminators 240 areoperated 1842 to provide IR with a second digital code. In the system1800, the back light assembly 1870 again includes a patterned polarizer1872 sandwiched between the LC display 210 and the Fresnel lens 260 anda switch polarizer 1874 placed near the light bar 1890. However, thesystem 1800 differs in that the back light assembly 1870 includes an IRdigital code receiver 1873 that operates to switch operation of theswitched polarizer 1874 to synchronize its operation with operation ofthe two illuminators 1842, 1843 (e.g., to polarize the output of lightbar 1890 to display a left eye image with LC display 210 when the leftilluminators 240 are operated as determined by receipt of IR with thesecond digital code 1842 rather than the first digital code).

In FIG. 19, a 3D display system 1900 is shown that includes a back lightassembly 1970 that again calls for a patterned polarizer 1972 to beplaced between the LC display 210 and the focusing element 260. In thiscase, a polarization rotator is not used but, instead, a pair 1990 oflight bars is used for each row of illuminators 240, 241 and viewers205, and one has its output light polarized with a vertical polarizer1992 and one with a horizontal polarizer 1994. An input or controlsignal 1976 is used to switch between use of the two light bars 1990such that the back lighting provided switches between vertical andhorizontal polarization (or left and right frame display) as shown withthe patterned polarizer 1972 alternating between acting as a verticalpolarizer (as shown at 1974) and a horizontal polarizer (as shown at1975). A similar control signal is used to switch between operation ofthe two illuminators 240, 241 such that one is operated concurrentlywith one of the light bars 1990 so as to switch between presenting leftand right eye images to the left and right eyes of each viewer 240, 241.

FIG. 20 illustrates a 3D display system 2000 similar to that of thesystem of FIG. 17 but using a different arrangement for selectivelyilluminating each viewer's face. As with system 1700, the back lightassembly 2070 includes a patterned polarizer 2072 between the LC display210 and the Fresnel lens 260 and further includes a switched polarizer2094 paired with a light bar 2090 (with the operation of the switchedpolarizer 2094 controlled by a signal 2095 from a controller or synccircuit).

To provide synchronized IR illumination, the 3D display system 2000includes a head tracking camera 2080 that is used to determine thelocation of each face/head of the visitors 205 in the viewing space. Inthis manner, the left and the right sides of all the faces aredetermined by the tracking camera 2080, and, in response, a processorand/or software is used to provide a controlling signal to a left-rightside of face IR illuminating projector 2084 to cause the projector toswitch between projecting IR just on the left sides of the faces of theviewers 205 and on the right sides of the faces of the viewers 205. Thisleft-right-left-right and IR illumination by projector 2080 issynchronized in time with operation of the switched polarizer 2094 withsignal 2095 from a sync circuit or system controller.

In some of the above embodiments, a single Fresnel lens is used, butthis may be undesirable in some applications as this may limit theviewing angle (or width of the viewing space) that can be served by thedisplay system. To relieve the Fresnel narrow angle, 3D display system2100 shown in FIG. 21 includes an LC display 210 and a pair oforthogonally-arranged (or at least transversely arranged) Fresnel lenses260A and 260B spaced apart from the back of the LC display 210. A beamsplitter 2196 is provided between the two Fresnel lenses 260A and 260Bto split the received IR light from the LC display 210 (originating fromilluminators 240, 241 and being reflected from the left and right sidesof the face of viewers 205 in the viewing space) and direct it to thetwo lenses 260A and 260B.

A light bar 2190A is provided behind the first Fresnel lens 260A todetect IR light from the right side of the audience and to back lightthe LC display via beam splitter 2196 for the right side of the audienceof viewers 205. Similarly, a second light bar 2190B is provided behindthe second Fresnel lens 260B to detect IR light from the faces of theviewers 205 in the left side of the audience and back light the LCdisplay 210 for this portion of the audience.

FIG. 22 illustrates, with display system 2200, an alternate method towiden the angle at which audience members can view 3D without glasses.The system 2200 uses a single Fresnel lens 2260 but with a sheet ofoptical turning film 2268 applied to the surface of the LC display 2264closest to the audience. Turning films that may be used for film 2268(such as 90 degree turning film from the 3M Company, Vikuiti productline) include an array of linear microprisms, which collectively causelight entering one plane surface of the material to be split into twopaths divergent by 90 degrees. This film 2268 is mounted such that itssplitting axis runs vertically, causing light be split to be split alonga vertical axis so that it can serve two audience sections “A” and “B.”

As in earlier embodiments, each section has its members simultaneouslylit on the left and right sides of their faces by illuminators 2240. Thelight 2250, 2255 from each of the sections A and B is merged by theturning film and is focused by the Fresnel lens 2260 towards the lightbars 2290 (as shown with arrow 2257) via vertical diffuser 2280. Inorder to provide tracking for the two sections of the audience withoutinterference between them, the audience seating in a first section (A)is lower than in a second section (B). There are two sets of light bars2290 for each row of seats: a light bar for the upper 1^(st) row; onefor the lower first row; a light bar for the upper second row; one forthe lower second row; and so on. Interference between rows andindividual viewers is prevented by the conjugate optics nature of thesystem 2200.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the present disclosurehas been made only by way of example, and that numerous changes in thecombination and arrangement of parts can be resorted to by those skilledin the art without departing from the spirit and scope of the invention,as hereinafter claimed.

We claim:
 1. A display apparatus, comprising: a display element; adisplay controller first displaying a left eye image and seconddisplaying a right eye image on the display element; in a viewing spaceadjacent a display surface of the display element, an illuminatorassembly operable to provide infrared (IR) light in the viewing space;and a back light assembly generating visible light to back light thedisplay element only in response to reflection of portions of the IRlight from one or more viewers positioned at viewing locations in theviewing space, wherein the display element is transparent to thereflected portions of the IR light, whereby the reflected portions ofthe IR light passes through the display element prior to the reflectedportions striking the back light assembly to trigger the generating ofthe visible light to back light the display element, wherein the backlight assembly includes a light bar comprising a row of IR receiversdetecting the reflected portions of the IR light and a row of visiblelight sources each independently operating only when a paired one of theIR receivers detects the reflected portions of the IR light to providethe visible light to back light the display element, and wherein the IRreceivers detect the reflected portions of the IR light concurrentlywith the operating of the row of visible light sources to back light thedisplay element.
 2. The display apparatus of claim 1, wherein thedisplay element comprises a liquid crystal (LC) display that istransparent to the reflected portions of the IR light.
 3. The displayapparatus of claim 1, wherein the light bar is curved to follow thePetzval focusing surface of a focusing element positioned between the LCdisplay and the light bar.
 4. The display apparatus of claim 1, whereina vertical diffuser is applied adjacent to the light bar to verticallyshape light emitted from the light bar prior to the emitted light backlighting the display element whereby the emitted light provides a tallerhead box at the viewing locations.
 5. The display apparatus of claim 1,wherein an isotropic scatterer is positioned adjacent the visible lightsources, whereby light output by the light sources is evened out andwhereby gaps between the visible light sources are filled.
 6. Thedisplay apparatus of claim 1, further including a focusing elementpositioned between the LC display and the light bar to first focus thereflected portions of the IR light onto the row of the IR receivers andto second focus light from the visible light sources into the viewingspace through the LC display, whereby the LC display is back lighted. 7.The display apparatus of claim 1, wherein each of the IR receivers ispaired with one of the visible light sources and wherein each of thevisible light sources comprises a white light emitting diode (LED). 8.The display apparatus of claim 7, wherein the paired ones of the LEDsand the IR receivers are spaced apart less than 1 inch and wherein areceiving surface of the IR receiver and a light emitting surface of theLED are spaced apart an offset distance with the receiving surface moredistal to the LC display.
 9. The display apparatus of claim 7, whereinthe IR light comprises IR modulated at a high frequency and wherein theIR receivers are configured for detecting IR modulated at the highfrequency.
 10. The display apparatus of claim 1, wherein the illuminatorassembly comprises a number of left side IR illuminators and a number ofright side IR illuminators, wherein each of the left and ride side IRilluminators each comprises an IR source and a collimator for generatingthe IR light to the viewing space, and wherein at least one of the leftside IR illuminators is directed onto a left side of one of the viewinglocations for one of the viewers and at least one of the right side IRilluminators is directed onto a right side of one of the viewinglocations for one of the viewers.
 11. The display apparatus of claim 10,wherein the illuminator assembly is operated in time synchronized mannerwith the display element whereby the left side IR illuminators operateconcurrently with the first displaying and the right side IRilluminators operate concurrently with the second displaying.
 12. Thedisplay apparatus of claim 1, wherein the illuminator assembly comprisesa number of left side IR illuminators and a number of right side IRilluminators, wherein each of the left and ride side IR illuminatorseach comprises an IR source and a collimator for generating the IR lightto the viewing space, and wherein each of the IR illuminators isassociated with a differing one of the viewers to provide one of theright side IR illuminators and one of the left side IR illuminator foreach of the viewers proximate to right and left sides, respectively ofthe viewer's face.
 13. The display apparatus of claim 1, wherein each ofthe IR receivers is paired with one of the visible light sources andwherein each of the visible light sources comprises a set of coloredLEDs spaced apart an offset distance from a plane containing the lightbar, whereby chromatic aberration is at least partially corrected in afocusing element positioned between the LC display and the light bar.14. The display apparatus of claim 1, wherein the visible light isswitched between first and second polarizations to display the left eyeimages during the first displaying and to display the right eye imagesduring the second displaying and wherein the illuminator assembly isoperated to be synchronized with the visible light switching toilluminate a left side of each of the viewers with the IR light duringthe first displaying and to illuminate a ride side of each of theviewers with the IR light during the second displaying.
 15. A visualdisplay, comprising: a light modulator including a front side and a backside for receiving back light; a plurality of pairs of light emittersand IR receivers, wherein the IR receivers receive IR light emitted fromthe back side of the light modulator and, in response, the lightemitters emit the back light onto the back side of the light modulator;a Fresnel lens positioned between the back side of the light modulatorand the pairs of the light emitters and the IR receivers, wherein theFresnel lens defines a light path for the IR light and for the backlight through the light modulator to a viewer positioned at a viewinglocation a distance from the front side of the light modulator; anillumination source directing IR light onto the viewer proximate firstto a left eye of the viewer and second to a right eye of the viewer,whereby portions of the IR light from the illumination source reflectsoff of the viewer toward the front side of the light modulator fortransmission through the light modulator to the Fresnel lens fordirecting onto the defined light path for the IR light; and a controlmechanism coupled to each of the pairs of the light emitters and the IRreceivers, wherein the control mechanism operates to determine when oneof the IR receivers is receiving the IR light from the back side of thelight modulator and, in response, to trigger a paired one of the lightemitters to produce the back light.
 16. The display of claim 15, whereinthe pairs of the light emitters and the IR receivers are arranged inhorizontal and side-by-side rows.
 17. The display of claim 15, furtherincluding a synchronization element providing control signals to theillumination source such that the first and second directing of the IRlight is performed concurrently with operating of the light modulator tofirst display left eye images of a stereo media stream and to seconddisplay right eye images of the stereo media stream.
 18. A method forproviding a 3D experience without 3D glasses, comprising: illuminatingleft sides of a plurality of viewer faces with IR light; detecting theIR light reflected from the left sides of the viewer faces; concurrentlywith and only during the detecting of the IR light reflected from theleft sides of the viewer faces, emitting visible light through a liquidcrystal (LC) display operating to display a left eye image; illuminatingright sides of the viewer faces with IR light; detecting the IR lightreflected from the right sides of the viewer faces; and concurrentlywith and only during the detecting of the IR light reflected from theright sides of the viewer faces, emitting visible light through the LCdisplay operating to display a right eye image.
 19. The method of claim18, further including directing the IR light reflected from the left andright sides of the viewer paths to follow light paths for performance ofthe detecting steps and directing the emitted visible light along thelight paths to strike the left and right sides of the viewer faces. 20.The method of claim 18, wherein the illuminating of the left sides ofthe viewer faces is synchronized in time with the operating of the LCdisplay to display the left eye image and wherein the illuminating ofthe right sides of the viewer faces is synchronized in time with theoperating of the LC display to display the right eye image.